Biology of the non-parasitic phase of the cattle tick Rhipicephalus (Boophilus) microplus in an area of Amazon influence

BACKGROUND

Rhipicephalus (Boophilus) microplus is the most important tick species affecting cattle in the world. Under field conditions, the non-parasitic phase of R. (B.) microplus is unknown in the Amazon biome, including Brazil. The present study aimed to evaluate the non-parasitic phase of R. (B.) microplus in field (grass plots) and laboratory conditions.

METHODS

The study was conducted from September 2020 to April 2022 in an Amazonian region (Maranhão State, Brazil). We evaluated the biological parameters of R. (B.) microplus under laboratory and field conditions. Engorged females were exposed to experimental conditions every 14 days, totaling 20 months of study. The following biological parameters were observed: pre-oviposition period, egg mass incubation period, and maximum larval survival period.

RESULTS

Abiotic data (e.g., temperature and humidity) varied little throughout the year. Precipitation was the factor that varied the most throughout the year (dry ~ 30 mm3 and rain 400 mm3), and the parameters of pre-oviposition and pre-hatching are longer during the rainy season. A possible negative effect of the dry season on the percentage of hatched eggs was observed. Larval longevity in the plots of both control and free females was short (mean ~ 50-60 days), below that recorded for larvae under controlled conditions (mean ~ 95 days).

CONCLUSIONS

Rhipicephalus (Boophilus) microplus was able to complete its non-parasitic phase by producing host-seeking larvae in the pasture during all months of the study. The results indicate that R. (B.) microplus can complete up to six generations per year in biome Amazon. To our knowledge, this is the highest number of annual generations for R. (B.) microplus in Latin America.

Comparison between the Mission Plus device and gold standard methods for measuring hemoglobin concentrations and packed cell volumes in cattle

BACKGROUND

A point-of-care device that can provide immediate and reliable hemoglobin (Hb) concentrations and packed cell volumes (PCVs) would be useful in veterinary medicine.

OBJECTIVES

We aimed to compare the use of a human device (Mission Plus; MP) with a gold standard (GS) method for measuring Hb concentrations and PCVs in cattle blood.

METHODS

Blood samples from clinically healthy cattle (n = 122) were collected with or without an anticoagulant (K₂ EDTA). The GS and MP methods were compared with correlation coefficients. Passing-Bablok regression analyses were also performed, and the acceptability judgment was completed using Bland-Altman plots.

RESULTS

The CV_max for Hb values obtained using the GS method, the MP device without K₂ EDTA, and the MP device with K₂ EDTA were approximately 2.70%, 1.70%, and 2.0%, respectively, whereas the CV_max for PCVs was 0.90%, 1.83%, and 2.05%, respectively. A positive correlation (97.5% confidence interval) was observed between the Hb concentrations and PCV values detected using the MP and GS techniques in blood with and without K₂ EDTA. Bland-Altman plots showed agreement between the MP and GS methods. For Hb using blood collected with or without the addition of K₂ EDTA, the mean differences were -0.87 g/dL (95% CI: 1.35; -3.96) and 0.08 g/dL (95% CI: 2.16, -1.99), respectively. For PCVs using blood collected with or without the addition of K₂ EDTA, the mean differences were -3.75% (95% CI: 0.61. -8.12) and -0.88% (95% CI: 2.86, -4.62), respectively.

CONCLUSIONS

The MP device can be used to analyze Hb concentrations and PCVs in bovine blood to assist in field diagnoses.

Frequency of bovine cysticercosis in the state of Rondônia, Brazil

Bovine cysticercosis remains as one of the most important cause of carcasses and viscera condemnation in Brazilian slaughterhouses. However, the efficiency of post-mortem inspection for the diagnosis of this zoonotic disease is relatively low, and few available studies were performed through serological exams. This study evaluated the frequency of bovine cysticercosis in cattle herds located in different farms of the state of Rondônia, Brazil. Among the 987 animals slaughtered from 33 farms, 21 animals (Frequency: 2.13%; 95C.I. 1.23-3.03) were considered as positive through indirect ELISA and confirmed by Immunoblot tests and the cysticercosis was detected in 12 farms (36.36% - C.I. 95% 19.95-52.78). The disease was detected in the municipalities Vale do Paraíso (12.50%), Theobroma (8.11%), Guaporé (7.27%), Rolim de Moura (5.71%), Presidente Médici (5.0%), Ouro Preto do Oeste (4.69%), Nova União (1.77%), Nova Brasilândia d'Oeste (1.14%) and Ministro Andreazza (1.01%). Therefore, prophylactic measures should be taken to improve beef production, control bovine cysticercosis and reduce costs to public health in this Brazilian state.

Histopathology of the reproductive system of male sheep experimentally infected with Toxoplasma gondii

The aim of this study was to investigate the histopathological changes in reproductive system (testicles, epididymis, seminal vesicles, and prostate) of small male ruminants after Toxoplasma gondii infection. Eight sheep were inoculated with T. gondii: group I, four sheep (2.0 × 10(5) P-strain oocysts); group II, four sheep (1.0 × 10(6) RH-strain tachyzoites); and group III, two uninfected sheep maintained as control. Infection with T. gondii was confirmed by seroconversion (indirect fluorescent antibody test-IgG) in all the infected animals beginning on post-inoculation day (PID) 7. On PID 70, all the animals were euthanized and tissue samples (testicles, epididymis, seminal vesicles, and prostate) were collected and processed for histological analysis. The main changes detected were a focal mononuclear interstitial inflammatory infiltrate in the prostate and seminal vesicles; diffuse testicular degeneration associated with calcification foci and a multifocal mononuclear interstitial inflammatory infiltrate; and a mononuclear interstitial infiltrate and focal necrotic areas of the muscle fibers surrounding the seminal vesicles. The histopathological findings of this work, along with the detection of T. gondii in the examined parenchyma tissues (immunohistochemistry) and the results obtained by other authors examining different tissues, suggest that histological changes diagnosed in the reproductive system of rams infected with T. gondii are strongly suggestive of toxoplasmatic infection.

Preferential infection sites of Cysticercus bovis in cattle experimentally infected with Taenia saginata eggs

The preferential sites of infection of Cysticercus bovis were evaluated in the skeletal muscle and entrails of 25 cattle that were experimentally infected with Taenia saginata (2×10(4) eggs). Two other animals were not inoculated (control). Ninety days after inoculation, all the cattle were euthanized. The carcasses were deboned and dissected into 26 anatomical sections (masseter muscles, brain, tongue, esophagus, heart, diaphragm, lungs, liver, kidneys, spleen, top sirloin butt, bottom sirloin butt, outside round, top (inside) round, transversus abdominus, top sirloin cap, strip loin, full tenderloin, eye of round, knuckle, shoulder clod, foreshank, shank, chuck, back ribs, and tail muscles). The dissected tissues were sliced into 5mm sections. From the 25 cattle, 9258 C. bovis (cysticerci) were recovered; 75.02% (6946) of these were recovered from skeletal muscles and 24.98% (2312) from the entrails. A high parasitism level was found in the shoulder clod (12.55%), heart (11.02%), liver (9.48%), masseter muscles (8.51%), chuck (8.25%), strip loin and full tenderloin (7.26%), knuckle (6.63%), and back ribs (5.53%), totaling 69.23% (5738) of all of the detected cysticerci. On the other hand, there was a low C. bovis parasitism level in the brain, spleen, tail muscles, kidneys, esophagus, and diaphragm, representing just 3.9% of the total number of cysticerci. Given these results, we conclude that specific skeletal musculature regions, such as the shoulder blade, chuck, strip loin and full tenderloin, knuckle, back ribs and top round, which are not officially examined in many countries, are effective sites to efficiently screen C. bovis infection. To date, these regions have not been considered as preferential sites of C. bovis infection. Based on our work, however, these regions deserve greater attention from health inspectors because they contained a greater number of Cysticercus than the other regions of carcasses that are parasitized by T. saginata larvae.

Semen variables of sheep (Ovis aries) experimentally infected with Toxoplasma gondii

The influence of Toxoplasma gondii on semen variables and sperm morphology of sheep was evaluated in eight reproductive males distributed into three experimental groups: GI, three sheep inoculated with 2.0x10(5) of P strain oocytes; GII, three sheep infected with 1.0x10(6) of RH strain tachyzoites and; GIII two control sheep. Clinical (rectal temperature, cardiac and respiratory frequencies), parasite and serology exams (IIF) were realized. Sperm variables (volume, motility, vigor and concentration) and semen morphology for each sheep were also evaluated. Thus, semen and blood collections were assessed on post-inoculation days (PIDs)-1,3,5,7,11,14 and weekly thereafter up to PID 70. Clinical alterations were observed (hypothermia and anorexia) in infected sheep from groups GI and GII. Parasitic outbreaks were detected in five sheep. All the infected sheep produced antibodies against T. gondii from PID 5 onwards, reaching a peak of 4096 and 8192 for group GI and GII sheep, respectively. Differences (P<0.05) were observed regarding the ejaculate volume between the inoculated groups (oocytes and tachyzoites) and control. Even though experimental toxoplasmic infection resulted in clinical symptomology in the inoculated sheep, the minimal alterations in sperm pathologies could not be directly attributed to T. gondii.

[Associated arthropodes in the laying hen excrement]

A research about arthropode fauna in laying hen excrement was carried out in a poultry house in the State of São Paulo, from January 2001 to December 2002. The objective was to verify the frequency of Diptera and Coleoptera collected by Berlese funil and flutuation methods, and to show correlation between the collect methods and sazonality possible in the currents seasons. A total of 29,499 insects were collected from seventy five collects, being 16,702 Diptera (six families) and 12,797 Coleoptera (four families). Some arthropodes presented direct relation with the collect method, the seasons of the years and the rainfall precipitation, with significant increase in the number of insects collected in certain periods of the year.